If anybody is interested, I literally just finished a 3-gang relay kit that replaces ALL of your existing dual tank wiring so that you can run (for example) 2 1987 TBI sending units and run 2 Walbro 255 fuel pumps. I'll be listing these shortly in the FS section with pics! Prices are $319.99 for these harnesses and include a NEW 65 psi GM style selector valve!

__________________Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

Here is the basic harness layout for it-there is a main IGN control relay and (2) fuel pump relays-a LH and RH. The control relay activates the selector switch and the pumps as well as the GM style 6-port selector valve-which btw is NOT your standard NOS GM valve or parts store replacement-the one I include is rated to 65 psi.

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__________________Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

These look really nice, as always! I'll need to save some buckaroos, but I'd definitely be interested. I don't like the idea of my current factory setup where the Walbros are drawing all of their current through the 28 year old factory wiring and the selector switch.

No-not quick dis-connect....it has the standard barbed fittings but can still be used with SAE 30R9 rated clamp on fuel injection hose which is rated up to 180 psi. I just designed this kit so I dont have a link to it per se...just getting the word out I have them available now-both short and longbox fleet side.

__________________Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

These valves are rated to 65 psi and are plug and play to the 1987 GM fuel selector valves. If you buy one from AC Delco it will be marked Pollak just like the originals were. Many people have used these with the corvette fuel pressure regulator (58 psi) for LS/Late Vortec applications.

This LSx spec'd dual tank kit is going out tonight for a member in NM! I needed to finish drafting his harness diagram schematic for future troubleshooting and/or mods. On kits which significantly deviate from stock I design and include a color coded diagram using my graphics program-another benefit you don't get from the big harness companies! Then again, they don't offer what I do anyway!

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__________________Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

It uses a factory style switch but must be on/off not momentary. As long as it does not say depress fully you're good. I thought I listed the AC Delco/GM part number for it....if not I can look it up-it's still in dealers for about $8-9.

__________________Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

Gmachinz,
I'm struggling a little and thought maybe you could lend some insight. I've taken the path of dual tanks on my 84' 5.3 swap with the following:
1. Walbro 255's in the tank
2. 87' tanks
3. 87' sending units
4. Pollak 42-159 6 port selector valve
Now I'm a little confused about how I'm going to power my in-tank pumps and also my OEM switch says "depress fully"????? Clearly I'm a green hat as this is the first time I've ever attempted a frame off so any help or suggestions would be greatly appreciated.

You need to use a 1987 fuel tank switch-the TBI trucks didnt use the depress fully switches-those were momentary and powered a shuttle valve inside the selector to open/close LH or RH fuel tanks ports.

__________________Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

gmachinz,
Will your harness work as a "plug and play" solution with the 87' sending unit wiring ? If so do you have any available ? Looking to avoid the need to fabricate wiring based on this diagram that a Painless engineer drew for me today.

No-not quick dis-connect....it has the standard barbed fittings but can still be used with SAE 30R9 rated clamp on fuel injection hose which is rated up to 180 psi. I just designed this kit so I dont have a link to it per se...just getting the word out I have them available now-both short and longbox fleet side.

You specifically state these are for fleet side trucks, are the parts any different for a step side?

I have been looking into a setup like this for a while and will be looking into this setup more next year when I get closer to putting the truck back together. I appreciate the information on the switch itself as well as I did not know the fuel injection switch was different than the carb. switch.

I was reading the above - been considering swapping an LS into my truck with dual tanks. Got to ask about the stock fuel lines - would they be ok with the higher pressure pumps? I think the stock pumps are around 15 psi and LS needs about 58 psi. I would think stock steel lines are ok, but about about the rubber lines - would they need to be replaced with something else?